1. Field of the Invention
This invention relates to heated bonding tools. More particularly, the present invention relates to a novel heating element for a bonding tool which does not physically contact the bonding tool being heated.
2. Description of the Prior Art
Wire bonding and die bonding tools are well known in the semiconductor manufacturing art and have been classified in U.S. Class 219, subclasses 85 etc. and in Class 228, subclass 4.5 etc. Heretofore, such heated bonding tools fell into one of two general types. U.S. Pat. No. 3,641,304 illustrates a high efficiency heat block having a replaceable heating element mounted in the block and means for mounting die or wire bonding nibs onto the heat block. The heat block was made relatively large and was not insulated, thus, exposing machine operators to heat blocks whose temperature operated up to 700.degree. C. When replacing tools or making critical adjustments, accidents could and would occur.
U.S. Pat. No. 4,315,128 illustrates another high efficiency heating bonding tool having a thin film heating element permanently attached to and made a part of the bonding tool. This tool was capable of being heated to 600.degree. C. When the tool or the heater wore out, the tool was thrown away, thus, tools could be thrown away before their useful life was expended.
Both types of tools create a heat hazard to operators who must adjust and replace the tools during production. More importantly, neither type of prior art tool could be easily adapted for use on modern high speed pick and place machines. One of the features of such pick and place machines is that the die or component being placed on a substrate or lead frame needs to have its position sensed in X, Y and theta after being picked up so that small pick up errors could be corrected prior to placement. Some of the electrodes on components and semiconductor devices are so small that the misplacement by a few microns could easily result in unusable finished product.
It would be highly desirable to provide a novel bonding tool and bonding tool heater which would be completely compatible with the latest high speed pick and place machines which are adapted for accurately placing components and chips on substrates and lead frames.